The principal axis is the
A) straight line drawn from the center of curvature to the mid point of the mirror.
B) straight line drawn from the center of curvature to any point of the mirror.
C) straight line drawn from the center of curvature to a point on the outer edge of the mirror.
D) straight line joining any two points on the mirror.
E) None of the other answers given is correct.

Question

Quizplus · Accepted Answer

The principal axis is the straight line drawn from the center of curvature to the midpoint of the mirror. This is because the principal axis is the axis of symmetry for the mirror, so it must pass through the center of curvature (the point equidistant from every point on the mirror) and the midpoint (the point equidistant from the top and bottom of the mirror).

The Principal Axis Is the